They're the 92 million who are in high school, college, and graduate school full-time, or who are raising the kids at home, or are disabled, or are over 65 years of age, retired and drawing Social Security.
Just 3% don't fit into any of those categories, or about 2.8 million people, that's it.
These are the truly "marginally attached" who aren't counted as unemployed.
The Bureau of Labor Statistics says about them:
"These individuals were not in the labor force, wanted and were available for work, and had looked for a job sometime in the prior 12 months. They were not counted as unemployed because they had not searched for work in the 4 weeks preceding the survey."
The BLS estimates they number 1.9 million in September. This analysis puts them about a million higher than that. Both can't be right but the margin of error is only 1%.
The government's estimate is close enough, I'd say.